1. Field of the Invention
The invention relates to a memory circuit, and in particular to a memory circuit capable of preventing false programming caused by power-up sequence.
2. Description of the Related Art
Fuse elements are widely used in semiconductor devices to record chip ID or serial number. In general, each fuse element includes a fuse capable of being selectively blown (i.e., opened or severed) in order to disconnect the fuse element from the remainder of the semiconductor circuit. For example, the fuse can be irradiated by a laser until it is opened, or opened by an electrical overcurrent capable of dissipating sufficient heat. Unlike using the laser, blowing the fuse by the electrical overcurrent can be performed even after the semiconductor device has been packaged and is referred as to “electrically programming” the fuse element. The fuse susceptible to such programming is referred to as an “electrically programmable fuse” or simply “e-fuse”, and most fuses can only be programmed once to provide 0 or 1 states corresponding to high or low resistance states or vice versa.